Knife sharpener



FIG. 1 is a front and bottom perspective view of a knife sharpener, showing my new design;

FIG. 2 is a rear and top perspective view thereof;

FIG. 3 is a front elevational view thereof;

FIG. 4 is a rear elevational view thereof;

FIG. 5 is a left side elevational view thereof;

FIG. 6 is a right side elevational view thereof;

FIG. 7 is a top plan view thereof;

FIG. 8 is a bottom plan view thereof; and,

FIG. 9 is a perspective view thereof, showing a handle of the knife sharpener in an unfolded position.

The broken lines in the figures illustrate portions of the knife sharpener that form no part of the claimed design. 

CLAIM The ornamental design for a knife sharpener, as shown and described. 